Effects of low-dose recombinant interleukin-2 in human malignancies.
OBJECTIVE
This article reviews the literature regarding the immunomodulatory activity and clinical efficacy of low-dose recombinant interleukin-2 (rIL-2) therapy. The aim of future rIL-2 biotherapies for the treatment of cancer is to standardize the lowest dosage of rIL-2 required to activate the in vivo anticancer immune response without harmful toxicity.


METHODS
Patients with various solid tumor malignancies have been treated with either subcutaneous or intravenous low-dose rIL-2 at doses ranging from < 1 MIU/m2/day to 6 MIU/day. In these studies the immunomodulatory effects of low-dose rIL-2 administration have been evaluated by measuring cytokine production and immune cell numbers and activity.


RESULTS
Prolonged and continuous injections of low-dose rIL-2 primarily increase activated T lymphocyte number, whereas intermittent and sequential injections of low-dose rIL-2 seem to induce a preferential increase in activated natural killer cells and eosinophils. Moreover, natural killer cells and eosinophil number increase progressively during the treatment, whereas T cells do not increase further after 2 weeks of treatment with low-dose rIL-2. The effect of low-dose rIL-2 is influenced by pretreatment systemic inflammation as well as neuroendocrine factors, such as pineal gland function.


CONCLUSIONS
Low-dose rIL-2 is not only less toxic than high-dose rIL-2 therapy, but is also the most physiologic immunotherapeutic strategy to activate the anticancer immune response in vivo.
Lissoni
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Division of Radiation Oncology, San Gerardo Hospital, Milan, Italy.
D002986:Clinical Trials as Topic; D016207:Cytokines / Q000502:physiology; D006801:Humans; D007167:Immunotherapy; D007376:Interleukin-2 / Q000008:administration & dosage / Q000276:immunology / Q000502:physiology*; D015213:Neuroimmunomodulation; D015375:Receptors, Interleukin-2 / Q000737:chemistry; D011994:Recombinant Proteins / Q000008:administration & dosage
D016207:Cytokines; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins